
[Federal Register: March 24, 2008 (Volume 73, Number 57)]
[Rules and Regulations]               
[Page 15397-15399]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr24mr08-4]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0303; Directorate Identifier 2008-NM-047-AD; 
Amendment 39-15441; AD 2008-06-29]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: We are adopting a new airworthiness directive (AD) for all 
Boeing Model 737-300, -400, and -500 series airplanes. This AD requires 
repetitive inspections of the downstop assemblies on the main tracks of 
the No. 2, 3, 4, and 5 slats and the inboard track of the No. 1 and 6 
slats to verify if any parts are missing, damaged, or in the wrong 
order. This AD also requires other specified actions, and related 
investigative and corrective actions if necessary. This AD results from 
reports of fuel leaking from a puncture in the slat track housing 
(referred to as the ``slat can''). We are issuing this AD to detect and 
correct loose or missing parts from the main slat track downstop 
assemblies, which could puncture the slat can and result in a fuel leak 
and consequent fire.

DATES: This AD is effective April 8, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of April 8, 
2008.
    We must receive comments on this AD by May 23, 2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, the regulatory evaluation, 
any comments received, and other information. The street address for 
the Docket Office (telephone 800-647-5527) is in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6440; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION;

Discussion

    Boeing has notified us that it has received numerous reports of 
fuel leaking from the slat track housing (referred to as the ``slat 
can'') on Boeing Model 737-300, -400, and -500 series airplanes. In all 
cases, there were no reports of a fire as a result of the fuel leaks on 
these airplane models. In some of the reports, the fuel leak was caused 
by loose or broken parts falling off the downstop assembly into the 
slat can, which were then subsequently driven into the slat can by the 
retracting slat track. This condition, if not corrected, could puncture 
the slat can and result in a fuel leak and consequent fire.

Other Related Rulemaking

    On August 28, 2007, we issued emergency AD 2007-18-52, amendment 
39-15197, to address the same unsafe condition on all Model 737-600, -
700, -700C, -800, -900, and -900ER series airplanes. That AD was 
published in the Federal Register on September 21, 2007 (72 FR 53928). 
That AD requires repetitive detailed inspections of the slat track 
downstop assemblies to verify that proper hardware is installed, one-
time torquing of the nut and bolt, and corrective actions if necessary. 
That AD resulted from reports of parts coming off the main slat track 
downstop assemblies and a resultant fire. That AD was issued to detect 
and correct loose or missing parts from the main slat track downstop 
assemblies, which could result in a fuel leak and consequent fire.
    Because the main slat track downstop assemblies of Model 737 
airplanes are similar in design to those of other Boeing airplane 
models, we have been working with the manufacturer to evaluate its 
remaining airplane models to determine if a similar unsafe condition 
exists on them. As a result, we may consider additional rulemaking as 
those evaluations are completed.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-57A1301, dated 
February 5, 2008. The service bulletin describes procedures for doing 
repetitive detailed inspections of the downstop assemblies on the main 
tracks of the No. 2, 3, 4, and 5 slats and the inboard track of the No. 
1 and 6 slats to verify if any parts are missing, damaged, or in the 
wrong order. The service bulletin specifies that the downstop assembly 
may be inspected using a borescope. The service bulletin also describes 
procedures for doing other specified actions, and doing related 
investigative and corrective actions if necessary. The other specified 
actions include a one-time torquing of the nut of the downstop assembly 
and a detailed inspection of the bolt to verify that the entire 
chamfered portion of the bolt protrudes beyond the outer surface of the 
nut. The related investigative action is a detailed inspection of the 
inside of the slat can for loose parts and damage to the wall of the 
slat can, which is done if any downstop assembly part is missing or 
damaged. The corrective actions include the following:
     Removing any loose downstop assembly part found in the 
slat can.
     Replacing any damaged slat can, or contacting Boeing for 
repair information.
     Replacing any missing or damaged downstop assembly part 
with a new or serviceable part.
     Removing and reinstalling the downstop assembly if any 
downstop assembly parts are in the wrong order, or if the entire 
chamfered portion of the bolt does not protrude beyond the outer 
surface of the nut after it is torqued.
    The service bulletin specifies doing the initial inspection within 
90 days and repeating the inspection thereafter at intervals not to 
exceed 4,500 flight

[[Page 15398]]

cycles. The service bulletin specifies doing the other specified 
actions within 90 days. The service bulletin specifies doing the 
related investigative and corrective actions before further flight 
after certain findings.

FAA's Determination and Requirements of This AD

    We are issuing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the(se) same type 
design(s). This AD requires accomplishing the actions specified in the 
service information described previously, except as discussed under 
``Differences Between the AD and Service Bulletin.''

Differences Between the AD and Service Bulletin

    For airplanes on which any downstop assembly part is missing or 
damaged, the service bulletin specifies doing a related investigative 
action--i.e., a detailed inspection of the inside of the slat can for 
loose parts and damage to the wall of the slat can. However, this AD 
allows operators to accomplish a borescope inspection of the inside of 
the slat can instead of a detailed inspection. We have coordinated this 
difference with Boeing.
    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this AD would 
require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.

Clarification of Slat Can Replacement

    Paragraph 3.B.5.a.(2) of the Accomplishment Instructions of the 
service bulletin specifies to either replace any damaged slat can or 
contact Boeing for repair information if any damaged slat can is found. 
Paragraph (f)(3) of this AD specifies, in part, that if an operator 
chooses to replace the damaged slat can instead of contacting Boeing 
for repair information, the damaged slat can must be replaced with a 
new slat can having the same part number.

Interim Action

    We consider this AD interim action. The manufacturer is currently 
developing a modification that will address the unsafe condition 
identified in this AD. Once this modification is developed, approved, 
and available, we might consider additional rulemaking.

FAA's Justification and Determination of the Effective Date

    Loose or missing parts from the main slat track downstop assemblies 
could puncture the slat can and result in a fuel leak and consequent 
fire. Because of our requirement to promote safe flight of civil 
aircraft and thus, the critical need to assure the structural integrity 
of the main slat track downstop assemblies and the short compliance 
time involved with this action, this AD must be issued immediately.
    Because an unsafe condition exists that requires the immediate 
adoption of this AD, we find that notice and opportunity for prior 
public comment hereon are impracticable and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety, and we did not provide you with notice and an opportunity to 
provide your comments before it becomes effective. However, we invite 
you to send any written data, views, or arguments about this AD. Send 
your comments to an address listed under the ADDRESSES section. Include 
``Docket No. FAA-2008-0303; Directorate Identifier 2008-NM-047-AD'' at 
the beginning of your comments. We specifically invite comments on the 
overall regulatory, economic, environmental, and energy aspects of this 
AD. We will consider all comments received by the closing date and may 
amend this AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this AD.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. ``Subtitle VII: Aviation 
Programs,'' describes in more detail the scope of the Agency's 
authority.
    We are issuing this rulemaking under the authority described in 
``Subtitle VII, Part A, Subpart III, Section 44701: General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979), and
    (3) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new AD:

2008-06-29 Boeing: Amendment 39-15441. Docket No. FAA-2008-0303; 
Directorate Identifier 2008-NM-047-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective April 8, 
2008.

Affected ADs

    (b) None.

[[Page 15399]]

Applicability

    (c) This AD applies to all Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from reports of fuel leaking from a puncture 
in the slat track housing (referred to as ``slat can''). We are 
issuing this AD to detect and correct loose or missing parts from 
the main slat track downstop assemblies, which could puncture the 
slat can and result in a fuel leak and consequent fire.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Repetitive Inspections and Corrective Actions

    (f) At the applicable time specified in Table 1 of paragraph 
1.E. of Boeing Alert Service Bulletin 737-57A1301, dated February 5, 
2008, except as provided by paragraph (f)(1) of this AD: Do a 
detailed inspection or borescope inspection of the downstop 
assemblies on the main tracks of the No. 2, 3, 4, and 5 slats and 
the inboard track of the No. 1 and 6 slats to verify if any parts 
are missing, damaged, or in the wrong order; and do all the other 
specified, related investigative, and corrective actions as 
applicable; by accomplishing all of the applicable actions specified 
in the Accomplishment Instructions of the service bulletin, except 
as provided by paragraphs (f)(2) and (f)(3) of this AD. Repeat the 
inspection thereafter at the applicable interval specified in Table 
1 of paragraph 1.E. of the service bulletin. Do all applicable 
related investigative and corrective actions before further flight.
    (1) Where the service bulletin specifies counting the compliance 
time from ``* * * the date on the service bulletin,'' this AD 
requires counting the compliance time from the effective date of 
this AD.
    (2) For airplanes on which any downstop assembly part is missing 
or damaged, a borescope inspection of the inside of the slat can for 
loose parts and damage to the wall of the slat can may be 
accomplished in lieu of the detailed inspection of the inside of the 
slat can that is specified in the service bulletin.
    (3) If any damaged slat can is found during any inspection 
required by this AD: Before further flight, either replace the slat 
can with a new slat can having the same part number or repair the 
slat can using a method approved in accordance with the procedures 
specified in paragraph (g) of this AD.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, Attn: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-
120S, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 
telephone (425) 917-6440; fax (425) 917-6590; has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane, and the approval must specifically refer to this 
AD.

Material Incorporated by Reference

    (h) You must use Boeing Alert Service Bulletin 737-57A1301, 
dated February 5, 2008, to do the actions required by this AD, 
unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207.
    (3) You may review copies of the service information 
incorporated by reference at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the 
National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, call 202-741-6030, or 
go to: http://www.archives.gov/federal_register/code_of_federal_
regulations/ibr_locations.html.

    Issued in Renton, Washington, on March 11, 2008.
Stephen P. Boyd,
Assistant Manager, Transport Airplane Directorate, Aircraft 
Certification Service.

 [FR Doc. E8-5702 Filed 3-21-08; 8:45 am]

BILLING CODE 4910-13-P
